For production of non-amino-organic acids including succinic acid by fermentation, usually, anaerobic bacteria such as those of the genera Anaerobiospirillum and Actinobacillus are used (Patent Document 1 and Patent Document 2, and Non Patent Document 1). The use of anaerobic bacteria makes yields of products high, while demanding many nutrients for proliferation of the bacteria. Therefore, there is a need of adding a large amount of an organic nitrogen source such as corn steep liquor (CSL) in a medium. The addition of abundant organic nitrogen source not only leads to an increase in cost of the medium but also leads to an increase in cost of purification for isolating the product, thereby being uneconomical.
In addition, methods, where aerobic bacteria such as coryneform bacteria are cultured under aerobic conditions to proliferate bacterial cells and then cells are harvested and washed to allow the cells as resting bacteria to produce non-amino organic acid without oxygen aeration, have been known in the art (Patent Document 3 and Patent Document 4). These methods are economical because the amount of organic nitrogen to be added for proliferating bacterial cells may be small and can proliferate cells sufficiently in a simple medium, but are susceptible to improvement in terms of the production amount of the organic acid of interest, the concentration thereof, and the production rate thereof per bacterial cell as well as simplification of the production process, and so on. Further, the production of non-amino organic acid by fermentation using a bacterium having an enhanced phosphoenol pyruvate carboxylase activity has also been reported (e.g., Patent Document 5).
The whole genome sequences of a coryneform bacterium have been identified to predict the functions of putative protein-coding sequences in the sequences (Non Patent Document 2). The gene referred to as sucE1 in the present invention is one of them and is predicted to encode permease. However, the actual functions of the gene have not been elucidated, and the involvement of the gene in a succinic acid synthetic pathway has been unknown yet.    Patent Document 1: U.S. Pat. No. 5,142,834 A    Patent Document 2: U.S. Pat. No. 5,504,004 A    Patent Document 3: JP 11-113588 A    Patent Document 4: JP 11-196888 A    Patent Document 5: JP 11-196887 A    Non Patent Document 1: International Journal of Systematic Bacteriology (1999), 49, 207-216    Non Patent Document 2: Appl. Microbiol. Biotechnol. 62(2-3), 99-109 (2003)